Antibody probe study of Ca2+ channel regulation by interdomain interaction within the ryanodine receptor

N-terminal and central domains of ryanodine receptor 1 (RyR1), where many reported malignant hyperthermia (MH) mutations are localized, represent putative channel regulatory domains. Recent domain peptide (DP) probe studies led us to the hypothesis that these domains interact to stabilize the closed state of channel (zipping), while weakening of domain-domain interactions (unzipping) by mutation de-stabilizes the channel, making it leaky to Ca2+ or sensitive to the agonists of RyR1. As shown previously, DP1 (N-terminal domain peptide) and DP4 (central domain peptide) produced MH-like channel activation/sensitization effects, presumably by peptide binding to sites critical to stabilizing domain-domain interactions and resultant loss of conformational constraints. Here we report that polyclonal anti-DP1 and anti-DP4 antibodies also produce MH-like channel activation and sensitization effects as evidenced by about 4-fold enhancement of high affinity [3H]ryanodine binding to RyR1 and by a significant left-shift of the concentration-dependence of activation of sarcoplasmic reticulum Ca2+ release by polylysine. Fluorescence quenching experiments demonstrate that the accessibility of a DP4-directed, conformationally sensitive fluorescence probe linked to the RyR1 N-terminal domain is increased in the presence of domain-specific antibodies, consistent with the view that these antibodies produce unzipping of interacting domains that are of hindered accessibility to the surrounding aqueous environment. Our results suggest that domain-specific antibody binding induces a conformational change resulting in channel activation, and are consistent with the hypothesis that interacting N-terminal and central domains are intimately involved in the regulation of RyR1 channel function.

An in situ hybridization and immunofluorescence study of GABAA and GABAB receptors in the vestibular nuclei of the intact and unilaterally labyrinthectomized rat

We investigated whether the production of the sixteen subunits of the GABA(A) receptors and of the different variants of GABA Breceptors are modulated in rat medial vestibular nuclei (MVN) following unilateral labyrinthectomy. Specific alpha1-6, beta1-3, gamma1-3 and delta GABA(A) and GABA(B) B1 and B2receptor radioactive oligonucleotides were used for in situ hybridization to probe sections of rat vestibular nuclei. Specific antibodies against alpha1, beta2, beta3 and gamma2 subunits of GABA(A) receptors and against GABA( B)receptors were also used to detect a potential protein expression modulation. No asymmetry was observed by autoradiography in the intact and deafferented MVN at any time (5 h to 8 days) following the lesion and for any of the oligonucleotide probes used. Also, no difference in the alpha1, beta2, beta3 and gamma2 of the GABA(A) and in the GABA(B) receptor immunohistochemical signal could be detected between the intact and deafferented vestibular nuclei at any time following the lesion. Our data suggest that GABA(A) and GABA Breceptor density changes most probably were not involved in the early stage of the vestibular compensation process, i.e., in the restoration of a normal resting discharge of the deafferented vestibular neurons and consequently in the recovery of a normal posture and eye position.

Mouse IgA inhibits cell growth by stimulating tumor necrosis factor- production and apoptosis of macrophage cell lines

Potent Fcalpha-mediated actions of IgA have previously been shown for myeloid cells from man, but much less is known in relation to murine cells. Here, we report that mouse monoclonal IgA, irrespective of their antigenic specificity, inhibit the proliferation of mouse macrophage cell lines. The anti-proliferative activity was manifested by both monomeric and polymeric mouse IgA, but not by mouse monoclonal IgG and IgM. Growth of J774 cells was significantly inhibited during the 4-8 days of logarithmic growth, followed by a subsequent recovery of cell numbers prior to the stationary phase. We demonstrated that IgA binds to J774 cells, stimulates tumor necrosis factor (TNF)-alpha production and induces apoptosis which is not dependent on NO or FAS/CD95. We also demonstrated that IgA, in synergy with IFN-gamma, induced TNF-alpha production and apoptosis of thioglycollate-elicited mouse peritoneal macrophages. Thus, the in vitro actions of IgA described may also play a regulatory role for mouse macrophages in vivo.

Anti-Sa antibodies: prognostic and pathogenetic significance to rheumatoid arthritis

Anti-Sa antibodies are detected in the serum of 20-47% of patients with rheumatoid arthritis. These antibodies have a high degree of specificity for the disease, and appear to identify a subset of early rheumatoid arthritis patients destined to have aggressive and destructive disease. It has recently been confirmed that anti-Sa antibodies are directed to citrullinated vimentin, thus placing them in the anti-citrulline family of autoantibodies. The Sa antigen has previously been shown to be present in synovium. This, along with the demonstration of citrullinated proteins in rheumatoid synovium, suggests that anti-Sa antibodies may play a pathogenetic role in the initiation and/or persistence of rheumatoid synovitis.

An engineered multidomain bactericidal peptide as a model for targeted antibiotics against specific bacteria

We constructed a peptide consisting of a staphylococcal AgrD1 pheromone fused to the channel-forming domain of colicin Ia and named it pheromonicin. This fusion peptide had bactericidal effects against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively), but not against Staphylococcus epidermidis or Streptococcus pneumoniae. Growth rates, vital staining and colony forming unit (CFU) counts showed that pheromonicin did not merely suppress growth but killed S. aureus cells. The specificity of pheromonicin was shown by the absence of bactericidal effects against an accessory gene regulator (agr) locus knockout of S. aureus, and a dose-dependent inhibition of the bactericidal effects of pheromonicin by competition with corresponding free AgrD pheromone. In vivo, all pheromonicin-treated mice survived administration of MRSA that was lethal to controls. No toxicity was detectable in human liver or renal cells in culture, or in livers, kidneys or spleens of pheromonicin-treated mice. The results suggest that these types of chimeric peptides may be of value as antibiotics against specific bacterial infections.

A simple method for immunocytochemical staining with multiple rabbit polyclonal antibodies

We report a single step, simple, repeatable, rapid and reliable technique for simultaneous immunocytochemical staining with two or more rabbit polyclonal antibodies. This technique, which we have dubbed the "Pretty Poly" method, is based on conjugating the antibodies with commercially available, fluorophore-tagged Staphylococcal protein-A (SP-A). Staining is illustrated at the calyx type presynaptic nerve terminal of the chick ciliary ganglion with antibodies directed against three nerve terminal proteins: neurofilaments of the axonal cytoskeleton, and two secretory vesicle proteins, SV2 and cysteine string protein (CSP). Images were deblurred with an iterative deconvolution protocol. Staining with a single polyclonal antibody was bright and had a resolution approaching light microscope limit. Treatment with two different polyclonal antibodies conjugated with contrasting dye-tagged protein-A resulted in double staining without significant crossover that was fully equivalent to the standard primary/secondary technique. The same single step protocol was used to stain with all three rabbit polyclonal antibodies or to combine the technique with a standard monoclonal primary/secondary antibody stain. Thus, the Pretty Poly protocol is a highly flexible, simple and yet effective staining technique that essentially solves the problem of co-staining with multiple polyclonal rabbit antibodies.

[Construction and expression of anti-CD3/ anti-Pgp Diabody]

The use of tumor antigen specific antibodies for the delivery of therapeutic agents offers the possibility of targeting therapy with reduced toxicity to normal tissues compared to conventional treatments. However, several factors restrict the use of anti-PGP monoclonal antibodies(Mabs). First, Pgp is expressed in normal tissues, particularly in epithelial and endothelial cells of the gastrointestinal tract, liver, kidney, blood brain barrier, choroids plexus and other organs. It plays a significant role to transport drugs and toxins in these organs. Therefore, anti-PGP antibodies in combination with cytotoxic compounds or radiolabelled antibodies should neither inhibit the activity of PGP, nor harm the cells which expressed PGP normally. BiMab exploit the specificity of Mab and ensures activation of cellular cytotoxic mechanisms which kill tumor cells only, but not harm normal cells. It will provide a strategy for resistant cancer therapy using anti-PGP antibodies. Second, Repeated administration of murine antibodies generates a strong human anti-mouse immune (HAMA) response in up to 50% of patients after the first dose, and appro ximately 90% following a second treatment. In an effort to reduce the toxicity and antigenicity, we focus to produce anti-PGP antibodies which have the binding activity only, but not inhibit the function of the "pump", and to construct a small and partially humanized recombinant molecule with dual specificity for both PGP and CD3 complex to activate the host immune response toward the tumour. PCR and overlap PCR were used to construct anti-CD3/ anti-Pgp Diabody. DNA sequence was analyzed by the Terminus of Dideoxy Nucleotide. The product was purified by affinity chromatography and analyzed by both the detection of western blot and size exclusion chromatography; its antigen-binding activity was examined by FACS, cellular RIA. Plasmid pAYZDCP which expressed the anti-CD3/anti-Pgp Diabody was constructed correctly. The diabody was recovered in high yield( up to 2mg/ L) after E-taq purification and predominantly(90%) as a dimer. The diabody can bind to Jurkat cells (CD3+) and K562/A02 cells(Pgp+). The affinities of the diabody were similar with the anti-CD3 ScFv or anti-Pgp ScFv, respectively. The anti-CD3/ anti-Pgp BsF(ab')2 was first recast into the diabody format and succeeded to obtain high level expression. The results of some biological activity experiments indicated that the diabody could bind to Jurkat cells and K562/A02 cells. Multidrug resistance can be reversed experimentally by a variety of drugs, among which the best known are verapamil and trifluoperazine, which unfortunately are of limited use in practice due to severe collateral cardiac toxicity. Anti-PGP x anti-CD3 diabody will provide another therapeutic strategy against multidrug resistance cancer.

The analysis of the fine specificity of celiac disease antibodies using tissue transglutaminase fragments

Celiac disease is an intestinal malabsorption characterized by an intolerance to cereal proteins accompanied by immunological responses to dietary gliadins and an autoantigen located in the endomysium. The latter has been identified as the enzyme tissue transglutaminase which belongs to a family of enzymes that catalyze protein cross-linking reactions and is constitutively expressed in many tissues as well as being activated during apoptosis. In a recent paper, we described the selection and characterization of anti-transglutaminase Igs from phage antibody libraries created from intestinal lymphocytes from celiac disease patients. In this work, using transglutaminase gene fragments, we identify a region of tissue transglutaminase recognized by these antibodies as being conformational and located in the core domain of the enzyme. This is identical to the region recognized by anti-transglutaminase Igs found in the serum of celiac disease patients.

Identification of the putative mannose 6-phosphate receptor (MPR 46) protein in the invertebrate mollusc

Mannose 6-phosphate receptor (MPR 300) protein was earlier affinity purified on phosphomannan gel from the membrane extracts of whole animal acetone powder of a mollusc, unio, in the presence of EDTA (Udaya Lakshmi, Y., Radha, Y., Hille-Rehfeld, A., von Figura, K., and Siva Kumar, N. (1999) Biosci. Rep. 19:403-409). In the present study we demonstrate that the unio also contains the putative mannose 6-phosphate receptor (MPR 46) that can be purified on the same gel in presence of divalent metal ions (10 mM each of calcium, manganese, and magnesium), and in the absence of sodium chloride and at pH 6.5. Chicken and Fish cell MPR 46 proteins were purified under these conditions (Siva Kumar, N., Udaya Lakshmi, Y., Hille-Rehfeld, A., and von Figura, K. (1999) Comp. Biochem. & PhysioL 123B:261-265). The authenticity of the receptor is further confirmed by its ability to react with the MSC1 antibody that is specific for MPR 46 protein. Additional evidence for the presence of MPR 46 in molluscs could be obtained by metabolic labeling of mollusc cells Biomphalaria glabrata (Bg cells) with [35S] methionine and cysteine, and passing the labeled membrane extract on phosphomannan gel (at pH 6.5 and 7.0). On elution with mannose 6-phosphate, followed by immunoprecipitation of the column fractions, we identified the putative MPR 46 protein in the Bg cells. When Bg cell MPR 46 was deglycosylated along with chicken MPR 46 (control) both species yielded a single polypeptide corresponding to molecular mass of 26 kDa, suggesting that both contain the same receptor protein.

The "egg-egg" syndrome: occupational respiratory allergy to airborne egg proteins with consecutive ingestive egg allergy in the bakery and confectionery industry

Allergies to various inhalative allergens are a serious problem in the bakery and confectionery industry. Sensitization to wheat flour and enzymes such as alpha-amylase are a frequent cause of occupational asthma. Airborne egg allergens have been reported as another cause of respiratory allergy. We examined bakery and confectionery workers with respiratory symptoms due to egg aerosols. Skin tests (SPT), scratch tests (ST), nasal provocation tests (NPT) and serological examinations (IgE) were performed. Lung function was assessed by spirometry, and continuous registration of aerosols and particulates as well as gravimetric sampling was done at the workplace. Four bakery and two confectionery workers intensively exposed to airborne egg proteins suffered from conjunctivitis and rhinitis, four also from asthma. Subsequently, three of these four workers reported symptoms after ingestion of food that contained egg. SPT with commercial egg white and egg yolk extracts were negative in four cases. Only two employees had clearly positive SPT to commercial egg allergens and reacted also to wheat flour extracts. Scratch tests with native egg proteins were positive in four employees. Specific IgE to egg white and egg yolk were positive (CAP > or = 2) in three and in four cases, respectively, whereas they were negative in two cases. Elevated levels of specific IgE to lysozyme were detected in four employees. Two workers were sensitized to lysozyme but not to other egg proteins. The clinical relevance of egg sensitization was confirmed by continuous air sampling and by correlating the onset of the respiratory symptoms which were reflected by a significant decline (> or = 30%) of the forced one second capacity (FEV1) in two workers. Sieving of egg white powder and an inadequate spray station for liquid eggs were identified as sources of excessive allergen exposure. Bakery and confectionery workers exposed to airborne egg proteins are at risk of developing occupational asthma and subsequent nutritive egg allergy. To our knowledge, these are the first cases of inhalative egg allergy and subsequent nutritive egg allergy reported in the literature, which we refer to as the "egg-egg syndrome" in analogy to the already known "bird-egg" and "egg-bird" syndromes.

Identification of sequence, protein isoforms, and distribution of the hyaluronan-binding protein RHAMM in adult and developing rat brain

The protein RHAMM (for "receptor for hyaluronan-mediated motility"; CD168) is a member of the hyaladherin family of hyaluronan-binding proteins. RHAMM has a role in cell signaling, migration, and adhesion via interactions with hyaluronan, microtubules, actin, calmodulin, and components of the extracellular regulated kinase (erk) signaling pathway. Based on previous findings of potentially similar roles in neural cells in culture, we investigated the molecular characteristics, protein expression profile, and distribution of RHAMM in rat brain. Reverse transcriptase-polymerase chain reaction (RT-PCR) using RNA isolated from adult rat brain yielded a single RHAMM sequence of 2.1 kilobases encoding a protein of 82.4 kDa. RHAMM is subject to alternate splicing in other systems, but no RT-PCR evidence was found for splice variants in brain, although our analysis does not rule out this possibility. The amino acid sequence displayed homology with human and murine RHAMM (74% and 80%, respectively) but contained only one copy of a 21-amino-acid sequence that is repeated five times in the murine homologue. By using anti-RHAMM antibodies, several RHAMM isoforms were identified in brain. Immunohistochemically, RHAMM was found in the vast majority of neurons and in many oligodendrocytes throughout brain, with heterogeneous levels among cell populations, and was confined to the somata and initial processes of these cells. RHAMM was detected in neurons of cerebral cortex and most subcortical and brainstem structures at postnatal day 1 and exhibited an adult distribution pattern by postnatal day 5. High levels were detected in oligodendrocytes by postnatal day 10. The widespread expression of RHAMM in adult and developing brain implies a role for this protein and its ligand hyaluronan in key events of cell signaling and cytoskeletal regulation in the CNS.

Modulation of recombinant GABA receptor/channel subunits by domain-specific antibodies in Xenopus oocytes

To study interaction of specific antibodies with the GABA receptor/channel, antisera were raised against the extracellular domains of the GABAA receptor/channel beta2 subunit, gamma2 subunit and the GABAC receptor/channel rho1 subunit. The specificity of the antibodies was characterized by immunocytochemistry and by Western blotting of transfected FDC-P1 cells expressing recombinant GABA receptor/channel subunits. The effects of the antibodies on whole-cell currents in Xenopus laevis oocytes expressing homomeric recombinant GABA receptor/channel beta2, gamma2, and rho1 were studied using two-microelectrode voltage clamp. In the absence of GABA, anti-alpha2, anti-gamma2, and anti-rho1 antisera elicited whole-cell currents in oocytes expressing beta2, gamma2, and rho1 subunits, respectively. The effect of antibody on channel activation was concentration-dependent. The whole-cell currents induced by anti-beta2 and anti-gamma2 were several-fold greater than those induced by application of 100 microm GABA. In Xenopus oocytes expressing recombinant rho1 subunits, GABA-induced whole-cell currents were inhibited by the anti-rho1 antibody. In contrast, the GABA-induced whole-cell currents were potentiated several-fold by anti-beta2 and anti-gamma2 antibodies in Xenopus oocytes expressing homomeric beta2 and gamma2 subunits. Our studies indicate that antibodies specific to the N-terminal domain of GABA receptor/channel subunits can modulate the neurotransmitter receptor function.

Localization of A-type K+ channel subunit Kv4.2 in rat brain

Kv4.2, a voltage-gated K+ (Kv) channel subunit, has been suggested to be the key component of the subthreshold A-type K+ currents (I(SA)s) recorded from the specific subcellular compartments of certain CNS neurons. To correlate Kv4.2 localization with the I(SA)s detected, immunohistochemistry will be useful. Although the Kv4.2 immunostaining pattern in the hippocampus and cerebellum has been reported, the Kv4.2 antibody used was not specific. Furthermore, Kv4.2 localization in other brain regions remains unclear. In this report, we first demonstrated the specificity of a new Kv4.2 antibody, and then used it to examine Kv4.2 localization throughout adult rat brain by immunohistochemistry. At the cellular level, Kv4.2 was found in neurons but not glias. At the subcellular level, Kv4.2 was localized in the somatodendritic compartment of most neurons examined. Nevertheless, our preliminary data indicated that Kv4.2 might be also present in the axon/terminal compartment. At the functional level, our data indicates that Kv4.2 localization and I(SA) correlate quite well in some CNS neurons, supporting that Kv4.2 is the key component of some I(SA)s recorded in vivo.

Distribution of the high-affinity choline transporter in the central nervous system of the rat

In cholinergic nerve terminals, Na(+)- and Cl(-)-dependent, hemicholinium-3-sensitive, high-affinity choline uptake is thought to be the rate-limiting step in acetylcholine synthesis. The high-affinity choline transporter cDNA responsible for the activity was recently cloned. Here we report production of a highly specific antibody to the high-affinity choline transporter and distribution of the protein in the CNS of the rat. The antibody stained almost all known cholinergic neurons and their terminal fields. High-affinity choline transporter-immunoreactive cell bodies were demonstrated in the olfactory tubercle, basal forebrain complex, striatum, mesopontine complex, medial habenula, cranial nerve motor nuclei, and ventral horn and intermediate zone of the spinal cord. Noticeably, high densities of high-affinity choline transporter-positive axonal fibers and puncta were encountered in many brain regions such as cerebral cortex, hippocampus, amygdala, striatum, several thalamic nuclei, and brainstem. Transection of the hypoglossal nerve resulted in a loss of high-affinity choline transporter immunoreactivity in neurons within the ipsilateral hypoglossal motor nucleus, which paralleled a loss of immunoreactivity to choline acetyltransferase. The antibody also stained brain sections from human and mouse, suggesting cross-reactivity. These results confirm that the high-affinity choline transporter is uniquely expressed in cholinergic neurons and is efficiently transported to axon terminals. The antibody will be useful to investigate possible changes in cholinergic cell bodies and axon terminals in human and rodents under various pathological conditions.

Developmental expression of a unique carbohydrate antigen, Tn antigen, in mouse central nervous tissues

Using an anti-Tn monoclonal antibody, the Tn antigen was detected immunohistochemically in prenatal and early postnatal central nervous tissues. On embryonic day 9 (E9), the antigen was distributed throughout the single neuroepithelial layer in the neocortex and then became more prominent in the preplate than in the ventricular zone along with formation of the preplate. Following division of the preplate and concomitant formation of the cortical plate, distinct labeling of the neocortex occurred in the marginal, subplate and intermediate zones, whereas in the cortical plate and ventricular zone were virtually not immunostained. It is notable that thalamocortical afferent fibers were also immunostained specifically on E14. After birth, the localization of the antigen became less noticeable and by 3 weeks after birth, the antigen had substantially disappeared. In the developing cerebellum, prominent labeling was also observed in the molecular layer and outskirts of the cerebellar nuclei on early postnatal days. To characterize the glycoprotein bearing the Tn antigen biochemically, immunoblot analysis was performed. The glycoprotein, most of which was extracted with a salt solution, migrated as a broad smeared band corresponding to a molecular weight of about 250 kDa on SDS-PAGE. Among the various tissues examined, this glycoprotein was only detected in the brain and its amount increased until an early postnatal stage with a peak on postnatal day 3 (P3), and then decreased gradually with age. This spatially and developmentally regulated expression of the Tn antigen suggests that this antigen plays a significant role in brain development.

Ezrin, radixin, and moesin are components of Schwann cell microvilli

Ezrin, radixin, and moesin (ERM proteins), as well as the neurofibromatosis 2 (NF2) tumor suppressor merlin/schwannomin, all belong to the protein 4.1 family, yet only merlin is a tumor suppressor in Schwann cells. To gain insight into the possible functions of ERM proteins in Schwann cells, we examined their localization in peripheral nerve, because we have previously shown that merlin is found in paranodes and in Schmidt-Lanterman incisures. All three ERM proteins were highly expressed in the microvilli of myelinating Schwann cells that surround the nodal axolemma as well as in incisures and cytoplasmic puncta in the vicinity of the node. In all of these locations, ERM proteins were colocalized with actin filaments. In contrast, ERM proteins did not surround nodes in the CNS. The colocalization of ERM proteins with actin indicates that they have functions different from those of merlin in myelinating Schwann cells.

Tyrosine-phosphorylated extracellular signal--regulated kinase associates with the Golgi complex during G2/M phase of the cell cycle: evidence for regulation of Golgi structure

Phosphorylation of the extracellular signal-regulated kinases (ERKs) on tyrosine and threonine residues within the TEY tripeptide motif induces ERK activation and targeting of substrates. Although it is recognized that phosphorylation of both residues is required for ERK activation, it is not known if a single phosphorylation of either residue regulates physiological functions. In light of recent evidence indicating that ERK proteins regulate substrate function in the absence of ERK enzymatic activity, we have begun to examine functional roles for partially phosphorylated forms of ERK. Using phosphorylation site--specific ERK antibodies and immunofluorescence, we demonstrate that ERK phosphorylated on the tyrosine residue (pY ERK) within the TEY activation sequence is found constitutively in the nucleus, and localizes to the Golgi complex of cells that are in late G2 or early mitosis of the cell cycle. As cells progress through metaphase and anaphase, pY ERK localization to Golgi vesicles is most evident around the mitotic spindle poles. During telophase, pY ERK associates with newly formed Golgi vesicles but is not found on there after cytokinesis and entry into G1. Increased ERK phosphorylation causes punctate distribution of several Golgi proteins, indicating disruption of the Golgi structure. This observation is reversible by overexpression of a tyrosine phosphorylation--defective ERK mutant, but not by a kinase-inactive ERK2 mutant that is tyrosine phosphorylated. These data provide the first evidence that pY ERK and not ERK kinase activity regulates Golgi structure and may be involved in mitotic Golgi fragmentation and reformation.

Antigraft antibody-mediated expression of metalloproteinases on endothelial cells. Differential expression of TIMP-1 and ADAM-10 depends on antibody specificity and isotype

Endothelial cell (EC) interaction with antigraft antibodies (Abs) mediates EC injury and activation involved in vascular graft rejection. The aim of this study was to identify EC genes regulated in response to antigraft Ab binding that contribute to the endothelium alterations implicated in graft rejection or survival. By means of RNA differential display, 13 cDNA fragments corresponding to genes differentially expressed in ECs incubated with antigraft Abs were identified. Among these cDNAs were found the tissue inhibitor of metalloproteinase-1 (TIMP-1) and a desintegrin and metalloproteinase (ADAM-10). We demonstrated that TIMP-1 and ADAM-10 mRNA and protein expression was rapidly upregulated in ECs in response to antigraft Ab binding. Our data showed that TIMP-1 was upregulated in response to human IgG but not IgM and anti-galactosyl (Gal) alpha1-3Gal human xenogeneic Abs. In contrast, upregulation of ADAM-10 in ECs was shown to be mostly mediated by anti-Galalpha1-3Gal IgM Abs. Specific effects of human IgG and IgM xenogeneic Abs on endothelial transcripts indicate that different isotypes and specificities of Abs may mediate different EC changes. Our results suggest that interaction of ECs with antigraft Abs, according to their specificity, selectively induces synthesis and release of metalloproteinases and inhibitors, controlling proteolytic processes and immunological events that respectively contribute to graft rejection or survival.

VIP and peptides related to activity-dependent neurotrophic factor protect PC12 cells against oxidative stress

Oxidative stress is a common associative mechanism that is part of the pathogenesis of many neurodegenerative diseases. Vasoactive intestinal peptide (VIP) is a principal neuropeptide associated with normal development and aging. We have previously reported that VIP induced the secretion of proteins from glial cells, including the novel survival-promoter: activity-dependent neurotrophic factor (ADNF). ADNF-9, a nine amino acid peptide derived from ADNF, protects neurons from death caused by various toxins. In the present study, we examined the neuroprotective effect of VIP against oxidative stress in a pheochromocytoma cell line (PC12). In addition, a lipophilic derivative of VIP, Stearyl-Nle17-VIP (SNV), and two femtomolar-acting peptides: ADNF-9 and a 70% homologous peptide to ADNF-9, NAP were tested as well. PC12 cells were treated with 100 microM H2O2 for 24 h resulting in a reduction in cell survival to 35-50% as compared to controls. Addition of VIP or SNV prior and during the exposure to100 microM H2O2 increased cell survival to 80-90% of control values. Culture treatment with ADNF-9 or NAP in the presence of 100 microM H2O2 increased cell survival to 75-80% of control values. Messenger RNA expression analysis revealed that incubation with VIP resulted in a twofold increase in VIP mRNA, whereas NAP treatment did not cause any change in VIP expression, implicating different mechanisms of action. Furthermore, addition of an ADNF-9 antibody prevented the ability of VIP to protect against oxidative stress, suggesting that VIP protection is partially mediated via an ADNF-like protein.

Localization of voltage-gated K(+) channels in squid giant axons

We have localized the classical voltage-gated K(+) channel within squid giant axons by immunocytochemistry using the Kv1 antibody of Rosenthal et al. (1996). Widely dispersed patches of intense immunofluorescence were observed in the axonal membrane. Punctate immunofluorescence was also observed in the axoplasm and was localized to approximately 25-50-microm-wide column down the length of the nerve (axon diameter approximately 500 microm). Immunoelectronmicroscopy of the axoplasm revealed a K(+) channel containing vesicles, 30-50 nm in diameter, within this column. These and other vesicles of similar size were isolated from axoplasm using a novel combination of high-speed ultracentrifugation and controlled-pore size, glass bead separation column techniques. Approximately 1% of all isolated vesicles were labeled by K(+) channel immunogold reacted antibody. Incorporation of isolated vesicle fractions within an artificial lipid bilayer revealed K(+) channel electrical activity similar to that recorded directly from the axonal membrane by Llano et al. (1988). These K(+) channel-containing vesicles may be involved in cycling of K(+) channel protein into the axonal membrane. We have also isolated an axoplasmic fraction containing approximately 150-nm-diameter vesicles that may transport K(+) channels back to the cell body.

Effect of desialylation on binding, affinity, and specificity of 56 monoclonal antibodies against MUC1 mucin

We evaluated 56 monoclonal antibodies (MAbs), submitted to the ISOBM TD-4 Workshop, for changes in binding following desialylation of the MUC1 molecule and for epitope specificity. Antibody binding of MAbs was assayed by an ELISA method using microtiter plates coated with the MUC1 mucin obtained from supernatants of the ZR75-1 cell line. The MUC1 mucin was desialylated directly on the plate by treatment with neuraminidase. For each MAb, binding to untreated mucin was compared over a range of antibody concentrations. The concentration at which binding was half-maximal (K50) was determined for all antibodies whose binding reached saturation in the assay. Results showed that K50 values for MAb binding to untreated MUC1 mucin varied from 10(-10) to 10(-6) M. These data suggest that MAbs to MUC1 mucin bind with a broad range of intrinsic affinities. Desialylation was found to have variable effects on antibody binding, in that binding was either increased, decreased, or unchanged. No relationship was found between the apparent affinities for untreated mucin and changes in binding following desialylation. Among the 56 Workshop MAbs, 33 were found reactive with synthetic peptides which mimic the MUC1 tandem repeat. We determined the epitope specificity of the 33 MAbs by competitive binding using 10 amino acid peptides corresponding to various regions of the 20-amino acid tandem repeat domain of MUC1. All antibodies which recognized epitopes in the 1-10 amino acid region of the tandem repeat showed increased binding to desialylated mucin. Antibodies to other peptide epitopes showed no consistent pattern of change in binding following desialylation. Our results suggest that sialic acid residues on the MUC1 mucin may contribute either positively or negatively to antibody binding. In addition, our results suggest that improved antibody selection methods could provide MAbs with improved selectivity for cancer-derived mucin compared with mucin from normal tissues. This could form the basis of improved biomarker assays for breast cancer.

Nucleolin as the earliest target molecule of autoantibodies produced in MRL/lpr lupus-prone mice

To elucidate the autoantigen against which autoantibodies are produced in the earliest phase of the disease process of systemic lupus erythematosus (SLE), serum samples were collected individually and serially from 10 NZB/NZW F1 and 10 MRL/lpr mice. Using immunoblots with mouse thymoma cell (EL-4) lysates as substrates, all mice were found to generate autoantibody against an either 150-kDa, 110-kDa, 75-kDa, or 55-kDa molecule in as early as 4 weeks. Anti-DNA antibodies occurred almost at the same time or after those against these four molecules. The number of antigens reactive with autoantibodies in immunoblots increased gradually with age. Antibodies against histone molecules were produced after 8 weeks of age. Among the four antigens, the 110-kDa molecule was identified as nucleolin, which is an abundant nucleolar phosphoprotein. Nucleolin binds DNA, RNA, and nucleic acid-binding proteins such as histone H1. Nucleolin is a target of granzyme A of cytotoxic T cells, and autoantibodies against it are found in sera from patients with SLE as well as from those with various viral infections. These results indicate that nucleolin is one of the immunodominant molecules that break down self-tolerance and initiate autoantibody-spreading in a mouse model of SLE.

Relationship between allergic status and specificity of IgG antibody to inhaled allergens: the grass pollen model

BACKGROUND

We have previously reported that IgG antibodies from healthy individuals and patients suffering from non-seasonal mite allergy bind to different sets of epitopes on Der p 1, allowing almost complete discrimination of the populations.

OBJECTIVES

To confirm this observation in a seasonal allergy model where a clear relationship between allergic symptoms and exposure to the offending agent is established. To investigate whether the pattern of modified specificity is related to the differences in IgG subclass hierarchy usually exhibited by nonallergic and allergic populations.

METHODS

The capacity of individual sera from patients allergic to grass pollen and healthy individuals, including grass pollen-sensitized subjects, to prevent the binding of pooled IgG, IgG1, and IgG4 fractions from grass pollen-allergic patients and healthy individuals to solid-phase bound grass pollen antigen was evaluated in enzyme-linked immunosorbent assay (ELISA) using streptavidin-biotin technology. Specificity controls were performed using sera from patients allergic to cat dander and house dust mite.

RESULTS

The capacity of sera to prevent the antigen binding of allergic IgG averaged 84 +/- 5% for allergic sera and 53 +/- 6% for healthy sera (P < 0.001 by one-way anova). Conversely, using the antigen-binding capacity of healthy control IgG as reference, percentage inhibitions averaged 46 +/- 9% in grass pollen-allergic subjects compared with 80 +/- 4%, 82 +/- 2% in healthy individuals, and mite- and cat-allergic patients, respectively, resulting in two well-separated populations (P < 0.0001 by one-way anova). Similar results were found regardless of whether pooled IgG1 or IgG4 were used.

CONCLUSION

Together with previous data, our results define a new type of humoral signature in the immune response to inhaled allergens. Allergic and healthy status differ not only in the presence or absence of specific IgE antibody but also in the preferential expression of distinct IgG specificities that are better correlated with clinical manifestations and are unrelated to subclass distribution.

Combined treatment with surfactant and specific immunoglobulin reduces bacterial proliferation in experimental neonatal group B streptococcal pneumonia

Neonates suffering from group B streptococcal (GBS) pneumonia often lack type-specific opsonizing antibodies. We studied the influence of combined intratracheal treatment with surfactant and a specific antibacterial polyclonal antibody (IgG fraction) on bacterial proliferation and lung function in an animal model of GBS pneumonia. Near-term newborn rabbits received an intratracheal injection of either the specific IgG antibody, nonspecific IgG, surfactant, a mixture of surfactant and the antibody, or 0.9% saline. At 30 min the rabbits were infected with a standard dose (10(8)) of the encapsulated GBS strain 090 Ia. After 5 h of mechanical ventilation the mean estimated increase in bacterial number in lung homogenate (log10 colonies/g) was 0.76 in the antibody group, 0.92 in the nonspecific IgG group, 0.55 in the surfactant group, and 1.29 in the saline group. A mean decrease in bacterial number (-0.05) was observed in the group that received combined treatment with surfactant and antibody (p < 0.05 versus all other groups). Lung-thorax compliance was significantly higher in both groups of surfactant-treated animals compared with saline or IgG treatment. We conclude that in experimental neonatal GBS pneumonia combined treatment with surfactant and a specific immunoglobulin against GBS reduced bacterial proliferation more effectively than either treatment alone.